Open-Centre Hydraulic Distributor for Stable Negative Flow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing negative control systems in hydraulic pumps for small-sized operating machines suffer from imprecision and instability, leading to inefficiency and high energy dissipation, which are not suitable for electric vehicles due to the presence of control chokes that cause quadratic pressure increases and instability.
Innovation Solution
An open centre hydraulic distributor system with a directional valve, slide valve, and valve device that maintains a threshold pressure difference, using a negative control line to stabilize pump displacement and reduce energy dissipation, featuring a fixed displacement electric pump and pressure sensors for precise flow rate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If control chokes are used in negative control systems, then flow rate control is achieved, but quadratic pressure increases and instability occur
Solution Approach 1:
The patent removes the control choke from the system entirely, replacing it with a valve device that directly controls flow rate without causing quadratic pressure increases. The choke is extracted from the circuit and its function is redistributed to the valve device, eliminating the instability caused by the choke's pressure-flow relationship.
Solution Approach 2:
The patent introduces a valve device as an intermediary element between the pump and the free circulation line. This valve device mediates the flow rate control function, providing stable and precise control without the quadratic pressure characteristics of control chokes. The valve device acts as a mediator that decouples the direct relationship between flow rate and pressure that causes instability.
2Loss of energy
If variable displacement pumps are used for negative flow control, then energy dissipation is reduced, but system complexity increases
Solution Approach 1:
The valve device performs multiple functions: it controls flow rate, maintains pressure differential, and enables negative control operation. By making the valve device multi-functional, the system reduces overall complexity while achieving energy efficiency. The same component handles multiple control tasks that would otherwise require separate devices.
Solution Approach 2:
The system uses the pump's own discharge pressure to control its displacement through the negative control line, creating a self-regulating mechanism. The pump automatically adjusts its displacement based on system conditions without requiring external control systems, reducing complexity while maintaining energy efficiency.
3Device complexity
If fixed displacement pumps are used in open centre systems, then simplicity is maintained, but energy dissipation increases due to lack of flow rate control
Solution Approach 1:
The valve device acts as an intermediary that enables a fixed displacement pump to operate efficiently in an open centre system. It provides the necessary flow rate control and pressure management without requiring a variable displacement pump, thus maintaining system simplicity while reducing energy dissipation.
Solution Approach 2:
The patent replaces the need for complex variable displacement pump mechanics with a simpler valve-based control system. The valve device provides flow rate control through mechanical or electro-hydraulic means, substituting the complex internal mechanics of variable displacement pumps with a simpler external control mechanism.
4Loss of energy
If negative control systems are implemented in electric vehicles, then energy efficiency improves, but control precision and stability are compromised
Solution Approach 1:
The system implements feedback through the negative control line that carries pressure signals from the pump discharge back to the pump control mechanism. This feedback loop enables precise and stable control by continuously adjusting pump displacement based on actual system conditions, achieving both energy efficiency and control precision.
Solution Approach 2:
The patent replaces imprecise mechanical control chokes with a more precise valve device that can be actuated by electronic or electro-hydraulic means. This substitution enables finer control resolution and better stability, meeting the precision requirements of electric vehicle applications while maintaining energy efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides precise and stable negative control with reduced energy dissipation, enabling efficient operation in electric vehicles by maintaining consistent flow rates independent of load variations and minimizing energy waste.
Implementation Method 1
a negative control line (L4) to pick up a pressure signal from the free circulation line (L2) in a position downstream of said at least one directional valve (SV1, SV2) and upstream of the slide valve (1), said negative control line (L4) being intended to bring a pressure signal to the pump (P) to perform the control of the negative type
Implementation Method 2
a valve device (2) configured to be activated when on the free circulation line (L2) a threshold value is reached that is given by the difference between a pressure value upstream and a pressure value downstream of said at least one directional valve (SV1, SV2), and to maintain said pressure difference equal to the threshold value
Data Source
AI summary
Open centre hydraulic distributor, comprising: a free circulation line connecting a supply line from a negative control pump to a discharge; a delivery line connecting the supply line to users; at least one directional valve that intercepts the free circulation line and the delivery line, so that it narrows a transit area of the free circulation line and opens a transit area of the delivery line, and vice versa; a slide valve arranged on the free circulation line downstream of the directional valve; a valve device that is activated when a threshold value of a pressure delta between upstream and downstream of the directional valve is reached, and maintains this pressure delta equal to the threshold value; a negative control line to pick up a pressure signal from the free circulation line downstream of the directional valve and upstream of the slide valve.